The invention relates to a method of and an apparatus for establishing a programmable exposure response of a camera, and more particularly, to such method and apparatus in which a programmable response which determines a combination of an exposure period and a diaphragm aperture can be shifted.
A camera with an automatic exposure control is known in which a combination of an exposure period and a diaphragm aperture can be varied by choosing one of a plurality of programmed responses as illustrated in FIG. 23 or 24 in response to one of a plurality of program signals (see Japanese Laid-Open Patent Applications No. 6,550/1976 and No. 151,626/1980). In each instance, a programmed response Pr is chosen as a reference, and other programmed responses are selected as an up-shift or a down-shift through a switch or through a resistor connection. For an up-shift, another programmed response P.sub.SU which employs a smaller exposure period TV for the same value of diaphragm aperture AV is selected. For a down-shift, a further programmed response P.sub.SD which employs a greater exposure period TV is selected.
A typical selection of a programmed response is illustrated by a flowchart shown in FIG. 25. In response to a shift input, the programmed response Pr is shifted either up or down while in the absence of a shift input, an EV value is calculated on the basis of the brightness of an object being photographed and a film speed, and utilizing the selected programmed response and EV value, an exposure period TV and a diaphragm aperture AV are calculated according to a program.
In the conventional program shift operation as illustrated by the flowchart of FIG. 25, the slope of the programmed response is changed (see FIG. 23) or the programmed response is caused to be translated (see FIG. 24) independently from an exposure period and a diaphragm value which correspond to a photographing situation. Accordingly, when a photographer desires to change the relationship between an exposure period and a diaphragm value by a given amount, difficulties are experienced that the number of steps depend on a particular EV value or the same step may be used for certain EV values.